Metal-resin composite container

ABSTRACT

Provided is a metal-resin composite container in which a flange portion formed of metal and a container portion formed of resin are joined together by overlapping of a flange vertical wall projecting from the flange portion and a container vertical wall projecting from the container portion. This overlapping prevents separation of the metal flange portion and the resin container portion caused by deformation of the resin container portion. The metal-resin composite container has a plurality of engagement parts each comprising a convex portion formed partially on the container vertical wall and a concave portion formed partially on the flange vertical wall and engaged with the convex portion. This convex-concave engagement allows gravity which acts on the container portion to be received by the concave portion of the flange portion and prevents cracking caused by excessive stress concentration.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a metal-resin composite container comprising a frame-shaped flange portion formed of metal and a container portion formed of resin and integrally joined to an opening peripheral portion of the flange portion.

2. Description of the Related Art

In reality, engine oil is often quite cold and low in lubrication efficiency in starting automobiles or the like. Besides, because of being formed of metal, conventional general oil pans have a problem in that the oil pans have high thermal conductivity coefficients and as a result tend to radiate heat of engine oil. So there is a demand for improvement of engine oil warming up characteristics.

It can be conceived to form an oil pan from resin, which has a low thermal conductivity coefficient. However, since the oil pan is fixed to a crankcase by bolts, the oil pan is necessary to have as high strength as those of metals in order to prevent creep deformation at a joint portion, and it is difficult for general resins to satisfy this need.

Therefore, it is thought to provide a metal-resin composite oil pan comprising an oil pan body formed of resin and a joint portion formed of metal. For example, PTL 1 discloses an engine cover formed of a metal-resin composite material and mentions that mating surfaces of a metal portion and a resin portion were subjected to processing for increasing contact area between these two portions.

PTL 2 also discloses an engine cover formed of a metal-resin composite material, and mentions that a mechanical lock is provided by burying a projection formed on a metal portion in a resin portion.

Furthermore, PTL 3 discloses a method for firmly joining a metal portion and a resin portion by a chemical reaction.

Therefore, upon combining these conventional techniques, it becomes possible to produce a metal-resin composite container comprising a frame-shaped flange portion formed of metal and a container portion formed of resin and integrally joined to an opening peripheral portion of the flange portion.

However, if the techniques of PTL 1 to PTL 3 are applied to an oil pan, since heat and oil weight act on the oil pan, the container portion may be deformed and separation can take place at a joint interface between the metal portion and the resin portion. For example, if the technique of PTL 1 and that of PTL 3 are combined, the metal portion and the resin portion will be joined together only chemically and separation may occur at the joint depending on deformation of the resin portion. If the technique of PTL 2 and that of PTL 3 are combined, the metal portion and the resin portion can be joined both chemically and mechanically. However, stress may be concentrated on an interface between the projection formed on the metal portion and the resin portion and cracks may develop from that region of the resin portion and cause separation.

LIST OF CITATIONS

[PTL 1] Japanese Unexamined Patent Publication No. 2010-031666

[PTL 2] U.S. Pat. No. 5,365,901

[PTL 3] Japanese Unexamined Patent Publication No. 2010-173274

SUMMARY OF THE INVENTION

The present invention has been made in view of these circumstances. It is an object of the present invention to provide a metal-resin composite container in which a metal flange portion and a resin container portion are jointed together in a manner to securely prevent separation of the metal portion and the resin portion caused by deformation of the resin container portion and cracking of the resin portion caused by excessive stress concentration.

The metal-resin composite container of the present invention, which solves the abovementioned problems, is a metal-resin composite container, comprising a frame-shaped flange portion formed of metal, and a container portion formed of resin and integrally joined to an opening peripheral portion of the flange portion, wherein:

-   -   the flange portion has a ring-shaped flange vertical wall         projecting toward the container portion, and the container         portion has a ring-shaped container vertical wall projecting         toward the flange portion, the flange portion and the container         portion being integrally joined by overlapping of the flange         vertical wall and the container vertical wall; and     -   the metal-resin composite container has a plurality of         engagement parts each comprising a convex portion formed         partially on an external surface or an internal surface of the         container vertical wall and a concave portion formed partially         on an internal surface or an external surface of the flange         vertical wall and engaged with the convex portion.

ADVANTAGES OF THE INVENTION

In the metal-resin composite container of the present invention, the flange portion and the container portion are integrally joined together by overlapping of the flange vertical wall and the container vertical wall. Therefore, a large contact area can be secured at a joint interface between the metal portion and the resin portion and joint strength improves.

The metal-resin composite container of the present invention further has a plurality of engagement parts each comprising a convex portion formed partially on an external surface or an internal surface of the container vertical wall and a concave portion formed partially on an internal surface or an external surface of the flange vertical wall and engaged with the convex portion. Owing to engagement of the convex portion and the concave portion in each of the engagement parts, gravity which acts on the container portion is received by the concave portion of the flange portion and as a result shear stress is prevented from acting on the joint interface. Furthermore, owing to the engagement of the convex portion and the concave portion, the contact area further increases. A synergic action of these further improves the joint strength.

It is desirable that at least a pair of engagement parts are provided in such positions as to oppose each other across an opening of the flange portion or the container portion. Owing to this construction, gravity which acts on the container portion can be uniformly received by both sides sandwiching the opening and stability of the joint strength improves.

It is also desirable that a fore end surface of the container vertical wall contacts a step portion formed on the internal surface or the external surface of the flange vertical wall, and a second convex portion formed on the fore end surface is engaged with a second concave portion formed on the step portion. Owing to this construction, the container portion can be more effectively prevented from being deformed in a diameter-increasing direction or a diameter-decreasing direction and stability of the joint strength further improves.

In addition, it is desirable that the metal flange portion and the resin container portion of the metal-resin composite container of the present invention are joined together by using the method recited in PTL 3. Owing to this construction, stability of the joint strength further improves.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] FIG. 1 is a perspective view of an oil pan according to a first preferred embodiment of the present invention.

[FIG. 2] FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1.

[FIG. 3] FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1.

[FIG. 4] FIG. 4 is an enlarged view of relevant parts of FIG. 3.

[FIG. 5] FIG. 5 is a cross-sectional view of relevant parts of a mold for insert molding in which a flange portion is placed.

[FIG. 6] FIG. 6 is an enlarged cross-sectional view of relevant parts of an oil pan according to a second preferred embodiment of the present invention.

[FIG. 7] FIG. 7 is an enlarged cross-sectional view of relevant parts of an oil pan according to a third preferred embodiment of the present invention.

[FIG. 8] FIG. 8 is an enlarged cross-sectional view of relevant parts of an oil pan according to another modified version of the third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A metal-resin composite container of the present invention comprises a frame-shaped flange portion formed of metal, and a container portion formed of resin and integrally joined to an opening peripheral portion of the flange portion. The metal flange portion can be provided with bolt holes for fastening to a mating member. The material of the flange portion is not particularly limited, and examples of the material include copper, nickel, tin, gold, silver, aluminum, iron, magnesium, chromium, tungsten, zinc, lead, and the like and their alloys including aluminum alloys, stainless steels, and brass.

Moreover, the material of the container portion is not particularly limited, and examples of the material include engineering plastics such as polyphenylene sulfide, polyamide, and polybutylene terephthalate, and general-purpose resins such as polyethylene, polypropylene, polystyrene, and polyvinyl chloride. Engineering plastics are preferred because characteristics (heat resistance, etc.) of the composite container improve.

The flange portion has a ring-shaped flange vertical wall projecting toward the container portion, and the container portion has a ring-shaped container vertical wall projecting toward the flange portion, the flange portion and the container portion being integrally joined by overlapping of the flange vertical wall and the container vertical wall. The flange vertical wall can be joined either to an outer side of the container vertical wall or to an inner side of the container vertical wall. It is desirable that the flange vertical wall and the container vertical wall are joined together all around, but, in some cases, can be partially unjoined.

Joining of the flange vertical wall and the container vertical wall can be carried out by a method using an adhesive, welding and so on, but it is desirable to employ the joining method recited in PTL 3 and molding the container portion integrally with the flange portion by insert molding placing the flange portion in a mold. That is to say, it is desirable that at least the flange vertical wall of the flange portion has a polar functional group on a surface thereof, and at least the container vertical wall of the container portion contains an adhesion-improving agent including an adhesive functional group to make an interaction with the polar functional group, and the flange vertical wall and the container vertical wall are joined together by the interaction between the polar functional group and the adhesive functional group.

The polar functional group is not particularly limited, and examples of the polar functional group include carboxyl groups, amino groups, hydroxyl groups, and aldehyde groups. It is preferable to employ at least one of carboxyl groups and amino groups because it can be easily provided on a metal surface.

The adhesive functional group is not particularly limited, and examples of the adhesive functional group include epoxy groups, carboxyl groups, amino groups and hydroxyl groups. An epoxy group is preferred because it readily reacts with a polar functional group.

The flange vertical wall and the container vertical wall only have to be overlapped with each other, but it is desirable that a fore end surface of the container vertical wall contacts a step portion formed on the internal surface or the external surface of the flange vertical wall. Upon employing this construction, a surface of the joint can be made even and contact area can be increased, so joint strength improves.

The metal-resin composite container of the present invention has a plurality of engagement parts each comprising a convex portion formed partially on an external surface or an internal surface of the container vertical wall and a concave portion formed partially on an internal surface or an external surface of the flange vertical wall and engaged with the convex portion. When a convex portion formed on an external surface of the container vertical wall is engaged with a concave portion formed on an internal surface of the flange vertical wall, the container vertical wall is joined to an inner side of the flange vertical wall. When a convex portion formed on an internal surface of the container vertical wall is engaged with a concave portion formed on an external surface of the flange vertical wall, the container vertical wall is joined to an outer side of the flange vertical wall.

For formation of an engagement part, upon forming a concave portion on a surface of a flange vertical wall previously in forming a flange portion, a convex portion can be formed in insert molding. Formation of the concave portion can be easily attained, for example, by cutting. Although it is sometimes difficult to form a concave portion on an internal surface depending on the shape of the flange portion, it is easy to form a concave portion on an external surface.

The number of engagement parts is at least two, and it is desirable that at least a pair of engagement parts are provided in such positions as to oppose each other across an opening of the flange portion or the container portion. Owing to this construction, gravity which acts on the container portion can be uniformly received by both sides sandwiching the opening and as a result stability of joint strength improves. Moreover, the convex portion in each of the engagement parts can take a variety of shapes such as a hemispherical shape and a claw shape. When the container portion is integrally molded by insert molding, the convex portion can have an undercut shape.

Length in a circumferential direction and thickness in a depth direction of the engagement parts can be arbitrarily determined as long as the engagement parts do not impair necessary strength to retain the shape of the flange vertical wall and the container vertical wall.

When a fore end surface of the container vertical wall contacts a step portion formed on an internal surface or an external surface of the flange vertical wall, it is desirable that one or more second convex portions formed on the fore end surface of the container vertical wall are respectively engaged with one or more second concave portions formed on the step portion of the flange vertical wall. Owing to this construction, the container portion can be more effectively prevented from being deformed in a diameter-increasing direction or a diameter-decreasing direction and stability of joint strength further improves. The shape of this second engagement part can be arbitrarily designed as long as it can provide necessary strength to retain the shape of the flange vertical wall and the container vertical wall.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in more detail by way of preferred embodiments.

First Preferred Embodiment

A metal-resin composite container according to a first preferred embodiment of the present invention is shown in FIG. 1. This metal-resin composite container is an oil pan for an automobile and comprises a frame-shaped flange portion 1 formed of an aluminum alloy and serving also as a crankcase lower part, and a container portion 2 formed of resin.

The flange portion 1 has a plurality of bolt holes 10 for fastening to a mating member by bolts. The container portion 2 has an opening 20 having the same shape as that of the flange portion 1 at an upper side thereof, and a peripheral portion of the opening 20 is joined to the flange portion 1. That is to say, the container portion 2 is integrally joined to the flange portion 1 by injection molding using the flange portion 1 as an insert in a mold.

A cross-sectional view taken along line A-A of FIG. 1 is shown in FIG. 2. The flange portion 1 has a flange vertical wall 11 projecting down toward the container portion 2, and the flange vertical wall 11 is formed all around the flange portion 1. An external step portion 12 having a greater depth is formed on an external surface of the flange vertical wall 11, and extends all around the flange vertical wall 11.

A container vertical wall 21 is provided vertically toward the flange portion 1 around the opening 20 of the container portion 2, and extends all around the container portion 2. An internal step portion 22 having a greater depth is formed on an internal surface of the container Vertical wall 21, and extends all around the container vertical wall 21. An internal surface of the internal step portion 22 contacts an external surface of the external step portion 12 in a manner to face each other, and the internal step portion 22 and the external step portion 12 are firmly joined together at an interface thereof. The external step portion 12 and the internal step portion 22 have an overlap length of 10 mm in a depth direction thereof.

A cross-sectional view taken line B-B of FIG. 1 is shown in FIG. 3 and an enlarged view of a portion surrounded by a dashed circle of FIG. 3 is shown in FIG. 4. As shown in FIG. 1, the flange portion 1 and the container portion 2 have flat portions 13, 23 having flat surfaces and curved portions 14, 24 projecting inward respectively from the flat portions 13, 23. FIG. 2, which is a cross-sectional view taken along line A-A of FIG. 1, shows a cross section of the curved portions 14, 24, and FIG. 3, which is a cross-sectional view taken along line B-B of FIG. 1, shows a cross section of the flat portions 13, 23.

At each of the flat portions 13, 23, an internal convex portion 25 is formed on the container vertical wall 21 in a manner to project inward, and engaged with an external concave portion 15 formed on the flange vertical wall 11. The internal convex portion 25 and the external concave portion 15 constitute one engagement part 3 of the present invention. The engagement part 3 has a width (a size in a direction perpendicular to the sheet of FIG. 4) of 10 mm. Twelve engagement parts 3 are formed in total in all the flat portions 13, 23 (eight positions) and two positions of each side perpendicular to sides having the curved portions 14, 24 (four positions).

A method for producing the metal-resin composite container of the present preferred embodiment will be discussed below.

First, a frame-like flange portion 1 is formed from an aluminum alloy by forging or casting. Bolt holes 10, a flange vertical wall 11, and an external step portion 12 are formed simultaneously with the flange portion 1. Then external concave portions 15 are formed on parts of an external surface of the external step portion 12 by machine processing. Since the external step portion 12 faces outward, the machine processing is easy. Moreover, since the external concave portions 15 are formed on flat portions 13, depth of the external concave portions 15 can be easily made uniform.

After the finished flange portion 1 is degreased, a carboxyl group is provided to the flange portion 1 by coating a polyacrylic acid solution at least on surfaces of the external step portion 12 and the external concave portions 15 and drying the coated flange portion 1 in a constant-temperature chamber. This flange portion 1 is held in a mold 4 for injection molding, as shown in FIG. 5.

Next, a container portion 2 is molded by melting and kneading polyamide resin and modified polyethylene obtained by modifying polyethylene as an adhesion-improving agent with glycidyl methacrylate and injecting the mixture into a cavity 40 of the mold 4. During this holding step, a reaction of a carboxyl group and an epoxy group occurs, so the external step portion 12 is firmly joined to the internal step portion 22, and the external concave portions 15 are firmly joined to the internal convex portions 25.

That is to say, according to the oil pan of the present preferred embodiment, since the flange vertical wall 11 and the container vertical wall 21 are joined together by overlapping each other, a sufficiently large contact area can be secured and joint strength is high. Even if engine oil weight is applied on the container portion 2, since the internal convex portions 25 and the external concave portions 15 are engaged with each other in the engagement parts 3, shear stress is prevented from acting on a joint interface between the external step portion 12 and the internal step portion 22. Moreover, since the flange portion 1 and the container portion 2 are joined together both mechanically and chemically, the oil pan of the present preferred embodiment can endure deformation of the container portion 2 and securely prevent separation of the external step portion 12 and the internal step portion 22.

Second Preferred Embodiment

A cross-sectional view of relevant parts of an oil pan according to a second preferred embodiment of the present invention is shown in FIG. 6. The present preferred embodiment is similar to the first preferred embodiment, except that an internal step portion 16 and internal concave portions 17 are formed on an internal surface of a flange vertical wall 11, and an external step portion 26 and external convex portions 27 are formed on an external surface of a container vertical wall 21, that is to say, the container vertical wall 21 is joined to an inner side of the flange vertical wall 11. The oil pan thus constructed also has similar effects to those of the first preferred embodiment.

Third Embodiment

A cross-sectional view of relevant parts of an oil pan according to a third preferred embodiment of the present invention is shown in FIG. 7. The present preferred embodiment is similar to the first preferred embodiment, except that an end surface concave portion 18 is formed on an end surface of an external step portion 12, and an end surface convex portion 28 is formed on a fore end surface of a container vertical wall 21 and engaged with the end surface concave portion 18.

The oil pan of the present preferred embodiment can have similar effects to those of the first preferred embodiment. In addition, even when stress acts so as to increase the diameter of the container portion 2, engagement between the end surface concave portion 18 and the end surface convex portion 28 prevents sheer stress from acting on a joint interface between the flange vertical wall 11 and the container vertical wall 21 and accordingly prevents separation of these walls 11, 21.

It should be noted that, as shown in FIG. 8, positions of the external concave portions 15 and the internal convex portions 25 are not limited to a fore end of the container vertical wall 21 but can be an intermediate portion or a base portion of the container vertical wall 21, and shapes of the end surface concave portion 18 and the end surface convex portion 28 are not particularly limited.

The preferred embodiments disclosed herein are illustrative and not restrictive. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described.

INDUSTRIAL APPLICABILITY

The metal-resin composite container of the present invention is not limited to the oil pans described as the preferred embodiments but can be used as a variety of products such as engine covers, chain covers and other automobile components, home electric appliances, and sundry goods. 

What is claimed is:
 1. A metal-resin composite container, comprising a frame-shaped flange portion formed of metal, and a container portion formed of resin and integrally joined to an opening peripheral portion of the flange portion, wherein: the flange portion has a ring-shaped flange vertical wall projecting toward the container portion, and the container portion has a ring-shaped container vertical wall projecting toward the flange portion, the flange portion and the container portion being integrally joined by overlapping of the flange vertical wall and the container vertical wall; and the metal-resin composite container has a plurality of engagement parts each comprising a convex portion formed partially on an external surface or an internal surface of the container vertical wall and a concave portion formed partially on an internal surface or an external surface of the flange vertical wall and engaged with the convex portion.
 2. The metal-resin composite container according to claim 1, wherein at least a pair of engagement parts are provided in such positions as to oppose each other across an opening of the flange portion or the container portion.
 3. The metal-resin composite container according to claim 1, wherein at least one of convex portions have an undercut shape.
 4. The metal-resin composite container according to claim 1, wherein a fore end surface of the container vertical wall contacts a step portion formed on the internal surface or the external surface of the flange vertical wall, and one or more second convex portions formed on the fore end surface are respectively engaged with one or more second concave portions formed on the step portion.
 5. The metal-resin composite container according to claim 1, wherein at least the flange vertical wall of the flange portion has a polar functional group on a surface thereof, and at least the container vertical wall of the container portion contains an adhesion-improving agent including an adhesive functional group to make an interaction with the polar functional group, and the flange vertical wall and the container vertical wall are joined together by the interaction between the polar functional group and the adhesive functional group.
 6. The metal-resin composite container according to claim 1, wherein the flange portion and the container portion have flat portions having flat surfaces and curved portions projecting inward respectively from the flat portions, and each engagement parts is formed on the flat portion. 